Magnetized Biochar as a Gold Nanocatalyst Support for p-Nitrophenol Reduction

The biomass use is of considerable ecological and economical interest and here, biochar, a by-product of biomass carbonization, is magnetized with Fe3O4 for its use as gold nanoparticle (NP) support towards catalysis of p-nitrophenol (4-NP) reduction. Biochar was synthesized from coffee straw biomass via pyrolysis, while magnetite functionalization was obtained using the precipitation method. The magnetite was identified by X-ray diffraction (XRD). The material had a specific surface area of 30 m2 g-1 and a zero point charge of 7.5. The gold NPs were deposited via reduction with NaBH4, which yielded Au and Fe3O4 NP of 4.61 and 10.9 nm, respectively. The materials were applied in the 4-NP reduction, Fe3O4Fe 3 O 4 NPs was observed. Remarkably, comparison with graphene oxide to which biochar resembles showed similar behavior, and the material was reused in several catalytic cycles.生物质的利用兼具重要的生态学与经济学价值。本研究中，作为生物质碳化副产物的生物炭（biochar）经四氧化三铁（Fe₃O₄）磁化改性后，可作为金纳米颗粒（NP）载体，用于对硝基苯酚（4-NP）还原的催化反应。研究通过热解咖啡秸秆生物质制备生物炭，并采用沉淀法完成磁铁矿功能化改性，利用X射线衍射（XRD）对所制备的磁铁矿进行了物相鉴定。该复合材料的比表面积为30 m²·g⁻¹，零点电荷为7.5。通过硼氢化钠（NaBH₄）还原法负载金纳米颗粒，最终分别得到粒径为4.61 nm的金纳米颗粒与10.9 nm的四氧化三铁纳米颗粒。将该材料应用于4-NP还原反应，可观测到四氧化三铁纳米颗粒的催化效果。值得注意的是，与结构类似的氧化石墨烯（graphene oxide）相比，该材料表现出相近的催化性能，且可多次重复用于催化循环反应。